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The  Conservation  of 
Food  Energy 


By 
Henry  Prentiss  Armsby,  Ph.D.,  LL.D. 

Director  of  the  Institute  of  Animal  Nutrition  of 
The  Pennsylvania  State  College 

Expert  in  Animal  Nutrition 
United  States  Department  of  Agriculture 

Foreign  Member 
Royal  Academy  of  Agriculture  of  Sweden 


.©♦o. 


Philadelphia  and  London 

W.  B.  Saunders  Company 

1918 


Copyright,  191 8,  by  VV.  B.  Saunders  Company 


PRINTED  IN  AMERICA 


For  many  years  investigators  in  this  and  other  coun- 
tries have  been  engaged  in  studying  the  values  of  foods 
and  feeding  stuffs  as  sources  of  energy.  The  following 
pages  are  submitted  in  the  belief  that  the  accumulated 
results  of  the  researches  in  this  and  other  laboratories 
are  capable  of  useful  application  and  should  if  possible 
be  made  of  service  in  the  present  food  situation. 

The  Pennsylvania  State  College, 

Institute  of  Animal  Nutrition. 

July,  1918 


CONTENTS 

PAGE 

Introductory 7 

Crude  Products  Inedible ^ 

Two  Methods  of  Utilization 8 

Their  Relative  Efficiency 8 

CH.\PTER  I 

The  Measure  of  Food  Values 11 

What  Food  Supplies 11 

Food  Energy 12 

Availability 1-^ 

Other  Factors I-' 

CHAPTER  II 

Energy  in  Human  Foods 16 

How  Determined 16 

Energy  Values 17 

CHAPTER  III 

The  Efficiency  of  the  Animal 18 

Recovery  of  Energy 18 

Net  Energy  Values 19 

Value  of  Forage 20 

CHAPTER  IV 

Food  Value  of  Increase  by  Animal 22 

Not  All  Edible 22 

Cattle 22 

Sheep 23 

Pigs 23 

Dairy  Cows 24 

3 


4  CONTENTS 

CHAPTER  V  PAGE 

The  Overhead  Feed  Cost 25 

Maintenance 25 

Maintenance  by  Forage  Crops 26 

Forage  Crops  for  Production 28 

CHAPTER  VI 

Wheat 29 

Feeding  Directly 29 

Milling 30 

Whole  Wheat  Flour 32 

CHAPTER  Vn 
Corn 34 

Feeding  Directly 34 

Milling 35 

Starch  and  Glucose 37 

Distilling 38 

Food  Value  of  Alcohol 39 

CHAPTER  VIII 

Barley 42 

Feeding  Directly 42 

Milling 42 

Brewing 43 

CHAPTER  IX 

Rye 46 

Feeding  Directly 46 

Milling 46 

Distilling 47 

CHAPTER  X 

Oats.    Rice.    Buckwtieat 48 

Feeding  or  Milling 48 


CONTENTS  5 

CIL\PTER  XI  PAGE 

Cottonseed 49 

Feeding  Directly 49 

Oil  Extraction 49 

Cottonseed  Flour 50 

CIL\PTER  XII 

Peanuts 51 

Feeding  Directly 51 

Oil  Extraction 52 

CIL\PTER  XIII 

Milk 53 

Butter  Making 53 

Cheese  Making 54 

CHAPTER  XIV 

SXMMARY 56 

Loss  in  Feeding 57 

Comparison  of  Animals 57 

Inedible  Products  Saved 58 

Milling  vs.  Feeding 58 

Vegetable  Oils 59 

Brewing  and  Distilling 59 


Index 61 


THE  CONSERVATION  OF 
FOOD  FNFRGY 

INTRODUCTORY 

Within  the  past  year  the  United  States  has  been 
rudely  awakened  from  its  dreams  of  plenty  to  be  faced 
with  the  urgent  problem  of  maintaining  the  food  supply 
for  itself  and  for  its  allies  in  the  face  of  all  the  diffi- 
culties incident  to  a  state  of  war.  A  National  Food 
Administration  has  been  created  and  entrusted  with 
large  powers  to  deal  with  all  phases  of  the  complex 
situation.  Questions  of  the  labor  supply,  marketing, 
price  control  and  transportation  are  being  dealt  with 
in  a  large  way,  while  nation-wide  propaganda  have 
been  launched  for  an  increased  food  production  by  the 
farmer  and  for  greater  economy  on  the  part  of  the 
consumer. 

Crude  Products  Inedible. — But  however  bountiful 
the  farmer's  crops,  in  their  crude  state  they  are  not 
human  food.  Some  of  them,  like  hay  or  the  straw  of 
his  grain  crops,  can  be  utilized  only  indirectly  by  feed- 
ing them  to  live  stock.  Others,  like  wheat  and  corn, 
while  they  can  also  be  used  as  animal  feeds,  are  com- 

7 


-  8        CONSERVATION  OF  FOOD  ENERGY 

monly  thought  of  as  being  directly  available  to  man. 
This,  however,  is  only  partially  true.  While  wheat 
may  be  fed  to  live  stock,  man  does  not  eat  wheat  but 
wheat  flour  and  a  bushel  (sixty  pounds)  of  wheat  yields 
only  about  forty-three  and  one-half  pounds  of  white 
flour  along  with  sixteen  and  one-half  pounds  of  milling 
offals  useful  only  as  stock  feed. 

Two  Methods  of  Utilization. — Two  alternatives,  then, 
are  open  for  the  conversion  of  farm  crops  into  human 
food: 

First,  they  may  be  fed  directly  to  animals  to  produce 
beef,  mutton,  pork  or  milk. 

Second,  such  of  them  as  admit  of  it  may  be  subjected 
to  various  manufacturing  processes — milling,  starch 
and  glucose  manufacture,  oil  extraction,  brewing,  dis- 
tilling—by which  a  greater  or  less  proportion  of  them 
is  converted  into  forms  acceptable  for  man's  use,  and 
the  by-products  of  these  operations  may  be  utilized  in 
the  production  of  meat  or  milk. 

Their  Relative  Efficiency. — In  any  scheme  of  food 
conservation  it  is  clearly  of  vital  importance  to  know 
the  relative  efficiency  of  the  various  methods  just  indi- 
cated. How  can  we  get  the  greatest  human  food  value 
out  of  a  bushel  of  wheat  or  of  corn?  Shall  we  feed  it 
to  live  stock  and  if  so,  shall  we  use  the  beef  steer,  the 
mutton  sheep,  the  hog  or  the  dairy  cow  as  the  mechan- 
ism for  converting  it  into  edible  products?  Or  shall 
we  manufacture  it  into  flour  or  table  meal  or  use  it 
as  a  source  of  starch  or  glucose  or  alcoholic  beverages, 


INTRODUCTORY  9 

and  feed  only  the  residues  of  these  processes  to  live 
stock,  and  if  the  latter  alternative  is  adopted,  to  what 
kind  of  live  stock  can  they  best  be  fed? 

This  publication  is  an  attempt  to  contribute  certain 
data  toward  the  solution  of  this  problem  as  regards 
some  of  the  more  important  farm  products.  Sections 
I  to  XIII  show  in  some  detail  the  methods  employed 
while  Section  XIV  attempts  to  summarize  the  broader 
teachings  of  the  inquiry.  In  addition  to  such  published 
data  as  could  be  found  the  author  is  under  obligation 
to  the  following  correspondents  for  information  regard- 
ing the  commercial  yields  of  foods  and  by-products  in 
the  various  manufacturing  operations  considered. 

Milling: — 

Prof.  Harry  Snyder,  The  Russell-Miller  Milling 
Co.,  Minneapolis,  Minn. 

Mr.  B.  W.  Dedrick,  Instructor  in  Milling  Engineer- 
ing, The  Pennsylvania  State  College. 

Director  W.  R.  Dodson,  Louisiana  Experiment 
Station. 

Glucose  Manufacture: — 
Mr.  0.  W.  Moffett,  Vice-President,  Corn  Products 
Refining  Co.,  New  York. 

Brewing  and  Distilling: — 
Dr.  H.  W.  Wiley,  Washington,  D.  C. 
Dr.    Robert   Wahl,    American    Brewers'    Review, 
Chicago,  111. 


10      CONSERVATION  OF  FOOD  ENERGY 

Mr.  Louis  Rosenfield,  Sunny  Brook  Distillery 
Co.,  Louisville,  Ky. 

Mr.  A.  M.  Breckler,  The  Eflorose  Sugar  Co.,  Cin- 
cinnati, Ohio. 

Oil  Production: — 

Mr.  H.  S.  Bailey,  Bureau  of  Chemistry,  U.  S. 

Dept^of  Agriculture. 
Mr.  Cecil  0.  Philips,  Sec'y,  Union  Seed  and  Fer- 
tilizer Co.,  New  York. 


THE  MEASURE  OF  FOOD  VALUES 

A  beefsteak,  a  slice  of  bread  and  a  glass  of  milk 
cannot  well  be  compared  directly  as  to  their  nutritive 
values.  Before  comparisons  such  as  those  indicated 
in  the  introduction  can  be  made  there  must  be  some 
common  standard  by  which  to  measure  the  food  values 
of  a  great  variety  of  diverse  materials.  As  a  prelim- 
inary to  the  choice  of  such  a  standard  a  brief  considera- 
tion of  the  three  main  purposes  which  the  food  serves 
appears  necessary. 

What  Food  Supplies. — First,  food  supplies  building 
material  for  the  growth  of  the  various  tissues  and 
organs  in  the  young  animal  and  for  their  maintenance 
and  repair  in  the  mature  one.  In  general  these  build- 
ing materials  are  of  two  kinds:  the  mineral  substances, 
which  are  required  for  the  bones  and  in  less  degree  for 
all  the  organs,  and  the  proteins  out  of  which  the  muscles 
and  other  working  parts  of  the  body  are  built  up. 

Second,  it  supplies  energy  for  the  various  activities 
of  the  internal  organs  which  are  necessary  to  sustain 
life,  and  for  the  performance  of  work.  The  food  is  in 
a  very  real  sense  the  fuel  of  the  body,  much  as  gaso- 
line is  the  fuel  of  the  auto  or  aeroplane,  supplying  the 
power  to  drive  it  and  incidentally  yielding  heat  to 
keep  it  warm. 

11 


12       CONSERVATION  OF  FOOD  ENERGY 

Third,  all  food  contains  minute  amounts  of  substances 
called  vitamines,  of  which  there  appear  to  be  two 
groups,  the  fat-soluble  and  the  water-soluble.  These 
vitamines  furnish  no  appreciable  amounts  of  building 
material  nor  of  energy  but  their  presence  is  essential 
to  the  various  operations  of  the  bodily  machinery, 
especially  in  growth.  In  a  very  crude  way  they  may 
be  said  to  be  somewhat  like  the  oil  which  neither  serves 
as  fuel  nor  repair  material  for  the  engine  and  yet  is 
essential  to  its  smooth  running. 

Food  Energy. — All  food  is  produced  primarily  from 
the  constituents  of  the  soil  and  the  air  by  the  higher 
(chlorophyl-bearing)  plants.  The  motive  power  for 
the  transformation  is  supplied  by  the  sun's  rays  and 
the  sun  energy  thus  absorbed  is  stored  up  in  the  pro- 
teins, starches,  fats  and  other  ingredients  of  the  plant. 
It  may  be  estimated  that  a  50-bushel  corn  crop  would 
contain  in  grain  and  fodder  nearly  ten  thousand  therms 
of  energy  per  acre,  sufficient,  if  it  were  all  converted 
into  heat,  to  raise  the  temperature  of  one  hundred 
tons  of  water  from  the  freezing  to  the  boiling  point  or 
equal  to  more  than  fifteen  thousand  horse-power  hours 
of  work.  It  is  this  stored-up  matter  and  energy  in 
agricultural  products  on  which  both  men  and  animals 
depend  to  supply  their  daily  needs. 

Of  these  needs  the  principal  one  is  that  for  energy. 
A  man  eats,  or  should  eat,  in  order  that  he  may  work 
and  work  is  simply  the  expenditure  of  energy.  Along 
with  energy  his  food  also  supplies  the  mineral  matters 


THE  MEASURE  OF  FOOD  V.\LUES        13 

and  proteins  necessary  to  keep  his  body  in  repair  and 
the  vitamines  required  to  ensure  its  normal  functioning, 
but  a  large  share  of  his  food  is  of  value  simply  as  body 
fuel. 

Availability. — To  answer  the  question  raised  in  the 
introduction,  therefore,  how  we  can  get  the  greatest 
human  food  value  out  of  wheat,  corn  or  other  products, 
what  we  need  to  know  primarily  is  how  much  of  the 
energy  stored  up  in  them  it  is  possible  to  render  avail- 
able for  running  the  human  machine.  While  it  is  true 
that  a  due  supply  of  mineral  matter,  proteins  and 
vitamines  in  the  food  is  equally  essential,  it  is  not, 
from  the  present  point  of  view,  equally  important, 
since  comparatively  slight  modifications  in  a  diet  sup- 
plying sufficient  energy  can  ordinarily  remedy  defici- 
encies in  this  respect.  For  this  reason  modern  studies 
of  human  dietaries  give  prominence  to  the  energy  re- 
lations and  the  problem  here  raised  will  be  discussed 
on  that  basis,  i.  e.,  we  shall  consider  how  much  energy 
in  forms  available  for  human  nutrition  can  be  obtained 
from  agricultural  products  in  the  various  ways  indi- 
cated in  the  introduction. 

Other  Factors. — It  is  true  that  the  problem  of  food 
conservation  or  of  rationing  an  army  or  a  people  is 
very  far  from  being  so  simple  a  thing  as  merely  sup- 
pl>'ing  a  certain  number  of  calories  of  energy  or  grams 
of  protein.  Questions  of  palatability,  of  dietary  habits, 
of  market  facilities,  and  of  costs  of  fuel,  labor,  trans- 
portation  and   marketing,    both   in   agricultural   and 


14      CONSERVATION  OF  FOOD  ENERGY 

manufacturing  industries,  all  have  to  be  considered. 
To  illustrate,  it  is  shown  in  subsequent  pages  that  the 
energy  of  corn  may  be  most  completely  utilized  by 
milling  it  and  using  only  the  corn  bran  for  stock  feed, 
and  that  considerable  energy  is  lost  when  corn  is  fed 
directly  to  animals.  It  does  not  follow,  however,  that 
we  should  ship  corn  meal  to  our  European  allies,  even 
if  spoiling  in  transportation  could  be  prevented,  since 
neither  their  dietary  habits  nor  their  domestic  economy 
render  the  general  use  of  com  bread  practicable.  Neither 
does  it  necessarily  follow  that  no  corn  should  be  fed 
to  live  stock,  even  were  the  supply  less  abundant  than 
it  is.  The  energy  of  grain  is  carried  largely  by  the 
starchy  materials  (carbohydrates).  Fats,  however,  are 
important  constituents  of  a  dietary,  both  as  affecting 
its  palatability  and  satisfying  quality  and  also  for 
another  reason  not  so  often  appreciated.  Fat  is  a 
much  more  concentrated  fuel  than  carbohydrates.  If 
the  attempt  were  made  to  sustain  a  man  doing  severe 
physical  work,  for  example,  one  of  our  soldiers  at  the 
front,  on  wheat  bread  alone  it  may  be  estimated  that 
he  would  have  to  eat  about  three  and  three-fourths 
pounds,  an  almost  impossible  quantity.  But  if  three- 
quarters  of  a  pound  daily  of  fat  salt  pork  and  two 
ounces  of  butter  were  furnished,  this  with  the  addition 
of  only  one  pound  of  bread  would  fully  supply  the 
necessary  protein  and  energy.^    Considerations  of  this 

'  It  scarcely  need  be  said  that  this  is  not  suggested  as  a  model 
ration.  It  is  intended  simply  to  illustrate  one  reason  for  the 
importance  of  a  due  amount  of  fat  in  the  diet. 


THE  MEASURE  OF  FOOD  VALUES        15 

sort  might  fully  justify  the  sacrifice  of  energy  incident 
to  the  production  of  pork  from  corn  for  the  sake  of 
the  smaller  weight  and  bulk  of  the  ration  and  the 
lessened  tonnage  required  for  its  overseas  transporta- 
tion, but  this  can  be  determined  with  certainty  only 
when  the  extent  of  the  sacrifice  is  known. 

The  foregoing  considerations  serve  to  illustrate  the 
way  in  which  conclusions  which  might  be  drawn  from 
energy  data  alone  are  subject  to  important  modifica- 
tions in  the  actual  administration  of  food  control. 
Nevertheless,  the  ultimate  object  of  all  food  control 
measures  is  the  recovery  of  the  greatest  practicable 
amount  of  food  value  from  the  products  of  the  soil 
and  a  fundamental  requirement  for  intelligently  com- 
bining all  the  diverse  factors  under  changing  condi- 
tions is  a  quantitative  knowledge  of  the  efficiency  of 
different  methods  of  procedure  in  conserving  the  food 
supply.  The  studies  of  human  and  animal  nutrition 
during  the  last  twenty  years  afford  data  for  an  approxi- 
mate computation  of  this  elBciency  and  the  results  for 
some  of  the  more  important  farm  crops  are  recorded 
in  the  following  pages. 


II 

ENERGY  IN  HUMAN  FOODS 

How  Determined. — The  recognized  method  of  esti- 
mating the  energy  supplied  in  human  foods  consists  in 
determining  first,  the  amounts  of  protein,  fat  and  carbo- 
hydrates contained  in  the  material  and  second,  the 
proportions  of  them  which  escape  utilization  when  the 
material  is  eaten.^  For  example,  the  average  of  a  large 
number  of  analyses  shows  one  hundred  pounds  of  wheat 
flour  to  contain  11.4  pounds  of  protein,  1.0  pound  of 
fat,  and  75.1  pounds  of  carbohydrates,  of  which  85  per 
cent.,  90  per  cent,  and  98  per  cent,  respectively  are 
digestible  when  the  flour  is  made  into  bread,  so  that 
one  hundred  pounds  of  wheat  flour  supply  9.7  pounds 
of  protein,  0.9  pound  of  fat  and  73.6  pounds  of  carbo- 
hydrates in  available  form.  But  each  pound  of  diges- 
tible protein  or  carbohydrates  has  been  shown  to  supply 
1.82  therms^  of  available  energy  and  one  pound  of  di- 

^  While  this  method  takes  no  account  of  the  mineral  ingre- 
dients nor  of  the  vitamines  it  is,  nevertheless,  sufficiently  accurate 
for  practical  purposes  under  ordinary  conditions  of  diet. 

2  For  the  present  purpose  a  therm  is  to  be  looked  upon  simply 
as  a  unit  of  energy — the  yard-stick  used  in  measuring  it.  Tech- 
nically, it  is  defined  as  the  energy  equivalent  to  the  heat  required 
to  raise  the  temperature  of  1000  kilograms  of  water  one  degree 
centigrade  or  3962  pounds  of  water  one  degree  Fahrenheit. 

16 


ENERGY  IN  HUMAN  FOODS  17 

gestible  fat  4.04  therms,  and  it  is  thus  easily  computed 
that  one  hundred  pounds  of  wheat  flour  supply  165 
therms  of  energy  for  man's  use.  Since  fat  and  carbo- 
hydrates are  simply  carriers  of  energy  the  foregoing 
statements  may  be  simplified  by  saying  that  100  pounds 
of  wheat  supply  9.7  pounds  of  protein  and  165  therms 
of  energy. 

Energy  Values. — In  the  following  table  are  given 
the  energy  values  as  thus  computed  of  the  food  prod- 
ucts considered  on  subsequent  pages: 

AVAILABLE  ENERGY  PER  100  POUNDSi 

Wheat  flour:  Therms 

"Straight"  or  "standard  patent" 165.0 

Whole  wheat 156.1 

Graham 150.5 

Corn  meal 165.5 

Hominy 165.0 

Glucose 167.4 

Com  oil 422.0 

Barley  flour 164.0 

Beer 21.0 

Rye  flour 163.0 

Oatmeal 185.0 

Polished  rice 168.5 

Buckwheat  flour 162.0 

Cottonseed  oil 422.0 

Cottonseed  flour 153.0 

Peanuts 256.0 

Peanut  oil 422.0 

Milk,  4%  fat 28.8 

Butter 361.0 

Cheese 195.0 

'  Chiefly  from  .\twater  and  Bryant,  U.  S.  Dept.  of  Agr.,  Oflice 
Expt.  Stas.,  Bui.  28  revised. 


Ill 

THE  EFFICIENCY  OF  THE  ANIMAL 

Recovery  of  Energy. — In  its  relation  to  the  conser- 
vation of  the  food  supply,  the  animal  is  a  transformer. 
The  grazing  steer  converts  the  crude,  inedible  sub- 
stances of  grass  into  flesh  and  fat;  the  stall-fed  dairy 
cow  manufactures  from  her  hay,  silage  and  grain  the 
totally  different  product  milk. 

Only  a  part,  however,  of  the  energy  and  protein 
contained  in  the  feed  of  the  animal  is  recovered  in  the 
meat,  milk  or  other  animal  products  secured.  In 
order,  then,  to  measure  the  contribution  made  by  the 
steer  or  the  cow  to  the  conservation  of  the  food  supply 
it  is  necessary  to  know  its  efficiency  as  a  converter — 
that  is,  what  proportion  of  the  protein  and  energy 
given  it  in  the  various  feeding  stuffs  is  recovered  in 
the  meat  or  milk  produced. 

As  regards  the  recovery  of  energy,  extensive  investi- 
gations by  rigid  scientific  methods,  both  abroad  and 
in  the  United  States,  during  the  past  two  decades 
have  yielded  results  which  seem  to  the  writer  suf- 
ficiently well  established  to  afford  a  foundation  on 
which  to  base  at  least  a  first  appro.ximation  to  the 

18 


EFFICIENCY  OF  THE  ANIMAL  19 

efficiency  of  the  animal  as  a  conserver  of  the  food 
supply.  As  regards  protein,  the  data  are,  unfortunately, 
far  less  satisfactory,  while  the  actual  recovery  in  prac- 
tice is  dependent  to  a  large  extent  on  the  proportion  of 
protein  in  the  ration. 

Net  Energy  Values. — The  facts  concerning  energy 
are  conveniently  expressed  in  what  have  been  called 
net  energy  values.  For  example,  one  hundred  pounds 
of  corn  contain  about  178  therms  of  energy.  When 
this  corn  is  fed  to  a  steer,  however,  about  43  therms 
escape  unused  in  the  various  excreta  and  about  50 
therms  more  are  lost  in  the  extra  heat  production 
which  always  follows  the  eating  of  feed.  The  remaining 
85  therms,  equal  to  47.75  per  cent,  of  the  entire  178 
therms,  is  the  portion  that  is  utilized  and  is  the  net 
energy  of  the  corn.  It  may  be  used  to  support  the  vital 
activities  of  the  animal  or,  if  he  is  already  receiving  a 
ration  sufficient  for  this  purpose,  it  may  be  utiUzed  for 
growth  or  fattening  and  be  stored  up  in  the  increase 
which  later  serves  as  human  food.  Similarly,  one 
hundred  pounds  of  average  timothy  hay  contain  about 
43  therms  of  net  energy  and  one  hundred  pounds  of 
oat  straw  about  35  therms,  that  is,  they  contribute 
these  amounts  to  the  nutrition  of  cattle.  Similar 
although  less  well  established  factors  are  also  available 
regarding  the  utilization  of  feed  by  the  milch  cow,  the 
sheej)  and  the  pig.  The  following  are  the  net  energy 
values  of  the  farm  products  considered  on  subsequent 
pages. 


20      CONSERVATION  OF  FOOD  ENERGY 
NET  ENERGY  VALUES  PER  100  POUNDS^ 


For  cattle 
and  sheep 

For  swine 

For  dairy 
cows 

Wheat 

Therms 
91.8 
85.5 
89.9 
93.7 
67.6 
77.3 
59.7 
78.3 

109.0 
14.3 
13.3 

Therms 

108.9 

118.8 

106.1 

123.7 

79.7 

111.0 

70.5 

97.7 

136.0 

14.7 

13.3 

Therms 
116.4 

Corn 

108.4 

Barley 

114.0 

Rye 

118.8 

Oats 

85.7 

Rice  (rough) 

Buckwheat 

98.1 

75.7 

Cottonseed 

99.3 

Peanuts 

138.3 

Skim  milk 

Buttermilk. 

Value  of  Forage. — When  materials  like  pasturage, 
hay  or  straw  are  used  to  produce  meat  or  milk  it  is 
apparent  that  they  are  indirectly  contributing  to  the 
food  supply  to  the  extent  of  their  net  energy  values 
and  the  same  thing  is  true  of  the  inedible  by-products 
of  the  various  manufacturing  processes  referred  to  in 
the  introduction.  Whatever  animal  products  may  be 
secured  in  this  way  are  a  direct  addition  to  man's 
food  supply.  With  grains  and  the  like,  on  the  other 
hand,  a  considerable  part  may  be  used  directly  as 
human  food,  leaving  only  the  by-products  to  be  used 
for  animal  production.  The  purpose  of  this  discussion, 
as  already  explained,  is  to  compare  these  two  methods 
of  utilization. 

'  Armsby:  The  Pennsylvania  Experiment  Station,  Bulletin  No. 
142,  July,  1916. 


EFFICIENCY  OF  THE  ANIMAL  21 

We  must  not,  however,  jump  to  the  conclusion  that 
this  may  be  accomplished  by  a  comparison  of  the 
energy  values  of  the  foregoing  table  with  those  of  the 
one  on  p.  17;  that  because,  for  example,  corn  meal 
has  an  energy  value  of  165.5  therms  for  human  con- 
sumption and  corn  one  of  85.5  therms  for  cattle,  half 
as  much  food  value  is  utilized  in  the  latter  case  as 
in  the  former.  Aside  from  the  fact  that  one  hundred 
pounds  of  corn  yield  only  about  85  pounds  of  table 
meal,  two  very  important  considerations  have  to  be 
taken  into  the  account,  as  is  shown  in  the  two  follow- 
ing sections. 


IV 

FOOD  VALUE  OF  INCREASE  BY  ANIMAL 

Not  All  Edible. — The  first  of  the  two  considerations 
just  mentioned  is  that  not  all  the  increase  made  by  the 
growing  or  fattening  animal  is  edible.  Part  of  it  is 
contained  in  the  bones,  which  have  practically  no 
nutritive  value.  Still  another  portion  is  found  in  the 
hide,  hair,  hoofs,  horns,  etc.,  and  still  another  in  the 
entrails.  The  dressed  carcass  amounts  to  from  55  to 
65  per  cent,  of  the  live  weight  in  cattle  and  sheep  and 
75  to  85  per  cent,  in  hogs  and  still  contains  the  bones 
and  more  or  less  other  waste.  While,  then,  a  steer 
may  store  up  85  therms  of  energy  in  his  body  (p.  19) 
as  a  result  of  eating  one  hundred  pounds  of  corn,  by 
no  means  all  of  this  is  available  for  human  food. 
What  proportion  is  so  available  will  depend  upon  the 
ratio  of  dressed  to  live  weight  and  upon  the  amount  of 
waste  in  the  dressed  carcass. 

Cattle. — Thus,  on  the  basis  of  analyses  of  the  entire 
bodies  of  medium  fat  cattle  by  Lawes  and  Gilbert 
and  by  Jordan  the  body  of  a  thousand-pound  steer 
contains  about  1392  therms  of  energy.  Such  cattle 
will  dress  about  58  per  cent.,  i.  e.,  a  one  thousand-poimd 
animal  yields  about  580  pounds  of  carcass  of  which 
about  17>2  per  cent,  or  101  pounds  is  inedible  waste. 

22 


FOOD  VALUE  OF  INCREASE  BY  ANIMAL  23 

The  remaining  479  pounds  of  edible  substance  con- 
tain about  678  therms  of  energy.  Finally,  when  the 
edible  portions  of  the  carcass  are  consumed  there  is  a 
further  loss  of  about  10^  per  cent,  due  to  the  fact 
that  the  meat  is  not  wholly  digestible,  so  that  out  of 
the  total  of  1392  therms  of  energy  contained  in  the 
body  of  the  steer  only  606  therms,  or  43>^  per  cent, 
of  the  whole,  is  actually  utilized  for  human  nutrition. 

In  a  precisely  similar  although  somewhat  more  com- 
plicated manner  it  may  be  computed  that  a  pound  of 
increase  in  live  weight  in  a  fairly  mature  fattening 
steer  contains  about  2.1  therms  of  energy  of  which 
about  1.11  therms,  or  53  per  cent.,  is  available  as  food 
for  man.  The  higher  percentage  arises  from  the  fact 
that  less  inedible  matter  is  produced  in  fattening  than 
in  growth. 

Sheep. — The  sheep  makes  a  somewhat  better  show- 
ing. On  the  average  one  pound  of  live  weight  of  a 
medium  fat  sheep  contams  1.517  therms  of  energy  of 
which  0.747  therm,  or  49.2  per  cent.,  is  available. 

Pigs. — The  pig  stands  above  either  the  steer  or  the 
sheep  in  this  respect,  partly  because  he  stores  up  more 
energy  in  a  pound  of  live  weight  but  chiefly  because  of 
a  much  higher  ratio  of  dressed  to  live  weight,  ranging 
from  75  to  85  per  cent,  as  compared  with  about  58 
per  cent,  for  cattle  and  60  per  cent,  for  sheep.  One 
pound  of  live  weight  of  a  medium  hog  may  be  estimated 
to  contain  2.186  therms  of  total  energy  of  which  1.975 
therms,  or  90.4  per  cent.,  is  available  to  man. 


24      CONSERVATION  OF  FOOD  ENERGY 

Dairy  Cows. — Finally  the  list  is  headed  by  the  dairy 
cow,  A  daily  yield  of  twenty-five  pounds  of  milk  with 
4  per  cent,  of  fat  will  contain  about  8.4  therms  of  total 
energy,  of  which  94  per  cent.,  or  7.9  therms,  is  avail- 
able for  man's  support,  as  compared  with  2.2  therms 
in  a  daily  gain  of  two  pounds  by  a  fattening  steer  or 
with  3  therms  in  a  daily  gain  of  one  and  one-half 
pounds  by  a  two-hundred  pound  pig. 


V 

THE  OVERHEAD  FEED  COST 

Maintenance. — The  second  consideration  which  must 
be  borne  in  mind  in  any  estimate  of  the  food  conserva- 
tion through  the  animal  is  that  a  certain  amount  of 
his  feed  is  consumed  to  keep  the  animal  machinery 
running,  much  as  a  factory  must  first  be  supplied  with 
enough  power  to  keep  in  motion  the  shafting,  belting 
and  machinery  in  general  before  any  product  can  be 
turned  out.  This,  which  we  may  call  the  overhead 
feed  cost,  is  commonly  spoken  of  as  the  maintenance 
requirement. 

Thus,  if  a  thousand-pound  steer  is  given  fourteen 
pounds  of  timothy  hay  daily  the  six  therms  of  net 
energy  which  it  contains  will  be  found  to  be  just  about 
sufficient  to  support  him  without  gain  or  loss  and  he 
will  neither  add  to  nor  subtract  from  the  food  supply. 
His  economic  efficiency  is  zero.  It  is  only  when  his 
feed  is  increased  beyond  this  lower  limit  that  he  begins 
to  store  up  food  material  for  man. 

Moreover,  his  usefulness  as  a  food  producer  will 
depend  upon  how  much  feed  he  can  consume  beyond 
the  minimum.  If  he  eats  twenty  pounds  of  the  hay 
daily,  he  will  be  getting  in  excess  of  his  maintenance 
requirement  2.6  therms  of  net  energy  to  be  stored  up 

25 


26      CONSERVATION  OF  FOOD  ENERGY 

in  his  body,  while  if  he  can  eat  twenty-five  pounds  of 
hay  he  will  have  4.75  therms  to  store  up.  In  the  one 
case  his  gain  will  be  about  0.13  therm  for  each  pound 
of  hay  fed  and  in  the  other  case  about  0.19  therm,  or 
46  per  cent.  more. 

What  is  true  of  a  simple  hay  ration  is  also  true  of 
the  mixed  rations  of  forage  and  grain  used  in  practical 
productive  feeding.  A  considerable  fraction  of  the 
feed  goes  simply  to  maintain  the  animal  and  the  profits 
of  the  feeding  are  largely  dependent  upon  how  much 
can  be  consumed  beyond  this  limit,  i.  e.,  upon  the  rela- 
tion of  the  total  volume  of  business  transacted  to  the 
overhead  cost. 

This  is  why  the  intensive  production  of  meat  or 
milk  usually  involves  the  use  of  grain  or  other  concen- 
trated feeding  stuffs.  Only  on  very  good  pasture  can 
an  animal  consume  enough  forage  in  excess  of  main- 
tenance to  support  rapid  production  and  so  ensure  the 
minimum  overhead  cost  per  unit.  Hay,  straw  and  the 
like  contain  so  much  innutritions  ballast  that  the  great- 
est amount  which  can  be  eaten  will  support  only  a 
relatively  small  production  with  a  correspondingly 
high  feed  expenditure  per  uni  t. 

Maintenance  by  Forage  Crops. — The  overhead  cost 
cannot  be  materially  reduced,  since  the  internal  organ- 
ization of  an  animal  is  not  accessible  to  improvement. 
The  best  we  can  do  is  to  meet  it  as  cheaply  as  possible. 
This  can  be  done  under  ordinary  conditions  by  the 
free  use  of  the  ordinary  home-grown  forage  crops, 


THE  OVERHEAD  FEED  COST  27 

which  are  usually  much  cheaper  sources  of  nutritive 
material  than  the  grains  or  their  manufacturing  by- 
products. Aside  from  the  milk  requirements  of  the 
very  young  animal,  it  has  been  demonstrated  to  be 
entirely  feasible  to  produce  good  yields  of  milk  or  well 
fattened  carcasses  not  only  of  cattle  and  sheep  but  of 
swine  as  well,  on  a  ration  containing  ample  roughage 
to  meet  the  requirements  for  maintenance,  leaving  the 
concentrates  to  be  applied  directly  to  the  production 
of  human  food. 

With  the  overhead  feed  cost  thus  provided  for,  it 
is  a  comparatively  simple  matter,  with  the  data  at 
hand,  to  estimate  with  a  good  degree  of  accuracy  how 
much  human  food  in  the  form  of  beef,  mutton,  pork 
or  milk  can  be  obtained  from  a  pound  of  corn  or  wheat, 
for  example,  or  of  their  various  by-products,  and  thus 
to  secure  an  approximate  answer  to  the  question  pro- 
posed at  the  outset. 

Of  course  the  maintenance  of  the  animal  by  means 
of  forage  crops  still  has  to  be  paid  for.  The  point  is 
that  he  docs  not  have  to  draw  on  the  supply  of  human 
food.  What  we  are  considering  here  is  not  how  animal 
foods  can  be  produced  most  cheaply,  but  how  the  food 
supply  as  a  whole  can  be  most  fully  conserved,  and 
while  the  two  are  intimately  related  it  is  the  second 
question  and  not  the  first  with  which  food  adminis- 
tration is  primarily  concerned.  Assuming  that  the 
animal  receives  at  least  enough  forage  to  supply  his 
maintenance  requirements,  the  attempt  will  be  made 


28      CONSERVATION  OF  FOOD  ENERGY 

in  the  following  sections  to  compute  what  amounts  of 
human  food  can  be  realized  from  some  of  the  more 
important  food  crops  of  the  farm  when  handled  in 
various  ways. 

Forage  Crops  for  Production. — Of  course  herbivorous 
animals  may  readily  eat  more  roughage  than  is  required 
for  maintenance  and  it  is  most  desirable,  both  from  the 
standpoint  of  economy  of  production  and  from  that 
of  food  conservation,  that  they  should  do  so.  In  par- 
ticular the  use  of  excessive  amounts  of  grain  in  the 
fattening  of  cattle  and  hogs,  as  has  been  the  practice 
in  many  sections,  involves  the  destruction  of  vast 
amounts  of  potential  human  food.  As  already  pointed 
out,  whatever  animal  products  are  obtained  from  forage 
crops  are  just  so  much  added  to  the  food  supply.  This, 
however,  need  not  interfere  with  the  proposed  compari- 
sons. Even  if  a  considerable  fraction  of  the  production 
is  at  the  expense  of  roughage,  whatever  concentrate  is 
added  to  such  a  ration,  within  reasonable  and  economic 
limits,  may  be  expected  to  produce  its  proportional 
quota  of  meat  and  milk  just  as  if  added  to  a  simple 
maintenance  ration. 

The  exact  methods  of  computation  will  be  illustrated 
as  we  proceed. 


VI 
WHEAT 

Wheat  is  preeminently  the  bread  grain  of  the  west- 
ern world.  It  is  subjected  on  a  large  scale  to  only 
one  manufacturing  process,  viz.,  milling.  It  therefore 
offers  a  convenient  starting  point  for  our  comparisons. 
In  one  hundred  pounds  of  average  wheat  there  are 
contained  about  183  therms  of  total  energy.  How 
much  of  this  can  be  recovered  for  human  nutrition? 

Feeding  Directly. — Wheat  is  not  ordinarily  fed  to 
domestic  animals,  yet  it  may  be  and  was  to  a  some- 
what considerable  extent  in  the  middle  west  not  so 
ver>'  many  years  ago.  If  one  hundred  pounds  of  it 
were  consumed  by  animals  whose  maintenance  require- 
ment was  already  provided  for,  the  available  data  as 
to  net  energy  value  (p.  20)  show  that  out  of  its  183 
therms  of  total  energy  there  would  be  retained  in  the 
body  or  in  the  milk  91.8  therms  by  beef  cattle  and 
sheep,  116.4  therms  by  dairy  cows  and  108.9  therms 
by  swine. 

But  by  no  means  all  of  these  amounts  are  available 
for  human  food.  It  was  pointed  out  under  IV  that 
much  of  the  energy  in  the  increase  of  cattle,  sheep 
and  swine  is  contained  in  the  offal  and  in  the  inedible 
portion  of  the  carcass  while  there  is  also  a  further 

29 


30      CONSERVATION  OF  FOOD  ENERGY 


small  loss  of  energy  when  the  edible  portion  or  the 
milk  of  the  cow  is  eaten  by  man.  For  example,  in  the 
case  of  beef  cattle  it  was  computed  that  only  43^  per 
cent,  of  the  energy  contained  in  the  body  of  the  animal 
is  actually  available  for  human  nutrition.  Out  of  the 
91.8  therms  of  energy  stored  up  in  the  body  of  the 
steer  as  the  result  of  feeding  one  hundred  pounds  of 
wheat,  then,  only  40.0  therms  would  contribute  to 
the  food  supply.  Precisely  similar  computations  for 
the  other  common  animals  give  the  results  which  fol- 
low. It  might  be  repeated  that  these  figures  show  the 
recovery  by  the  animal  after  the  power  required  to 
keep  its  bodily  machinery  running  has  been  provided 
by  other  materials: 


Wheat  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows 


Recovered  in 
animal  products 


Therms 
40.0 
45.2 
98.4 

109.5 


Percentage 
recovery 


22 
25 

54 
60 


Milling. — Taking,  now,  the  other  alternative,  let  us 
see  how  much  of  the  wheat  energy  can  be  recovered 
by  milling  the  wheat  and  using  only  the  offal  for  stock 
feed.  The  ordinary  commercial  milling  yields  about  73 
per  cent,  of  white  or  "straight"  flour  (including  a  httle 
"second  clear"  flour),  about  2  per  cent,  of  "red  dog" 
flour,  and  25  per  cent,  of  shorts  and  bran,  all  of  which 


WHEAT 


31 


are  ordinarily  used  for  feed  although  part  of  the  red 
dog  flour  can  also  be  used  as  an  admixture  with  the 
higher  grades  of  flour.  A  pound  of  "straight"  flour 
supplies  (p.  17)  1.65  therms  of  energy  available  to  man. 
The  73  pounds  obtained  from  one  hundred  pounds  of 
wheat  would  therefore  yield  120.5  therms,  or  consider- 
ably more  than  the  greatest  total  amount  recoverable 
in  animal  products,  while  in  addition  the  offal  may  be 
fed  to  stock. 

The  27  pounds  of  mixed  shorts,  bran  and  red  dog 
flour  would  contain  about  49.9  therms  of  total  energy, 
of  which  there  would  be  recovered  in  animal  products 
by  cattle  and  sheep  15.5  therms,  by  dairy  cows  19.6 
therms  and  by  swine  24.2  therms.  But,  as  is  the  case 
when  entire  wheat  is  fed,  only  part  of  these  amounts  is 
actually  available  for  man's  nutrition.  Making  the 
same  relative  deductions  as  before  for  the  inedible  and 
indigestible  portions  of  this  energy,  and  adding  to  the 
remaining  available  energy  the  120.5  therms  supplied 
by  the  73  pounds  of  wheat  flour,  we  find  there  would 
be  recovered  for  human  food  the  following  amounts: 


Recovered 
in  animal 
products 

Recovered 

in  "straight" 

flour 

Total 
recovered 

Percentage 
recovery 

Offal  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows. . . 

Therms 

6.8 

7.6 

21.9 

18.5 

Therms 
120.5 
120.5 
120.5 
120.5 

Therms 
127.3 
128.1 
142.4 
139.0 

70 
70 
78 
76 

32      CONSERVATION  OF  FOOD  ENERGY 

Evidently  wheat  makes  a  much  greater  contribution 
to  human  nutrition  when  it  is  converted  into  flour  and 
only  the  by-products  used  for  stock  feed  than  when  it 
is  consumed  directly  by  animals,  the  difference  being 
very  large  in  the  case  of  beef  and  mutton  production 
and  considerable  even  in  pork  and  milk  production. 

Whole  Wheat  Flour. — Wheat,  however,  may  be 
milled  to  yield  a  much  larger  percentage  of  flour  and 
less  offal  than  in  the  usual  commercial  process  and 
such  milling  has  been  strongly  urged  as  a  matter  of 
food  economy  as  well  as  for  other  reasons.  Some  idea 
of  the  extent  of  the  economy  which  may  thus  be 
effected  can  be  obtained  by  a  comparison  with  two 
familiar  products,  viz.,  whole  wheat  flour  and  graham 
flour.i 

In  the  production  of  whole  wheat  flour  about  one- 
half  of  the  coarse  bran  is  removed  while  in  the  manu- 
facture of  graham  flour  the  entire  wheat  grain,  includ- 
ing the  bran,  enters  into  the  flour.  The  resulting  flours 
contain  somewhat  less  energy  per  pound  than  "straight" 
flour,  viz.,  whole  wheat  flour  1.561  therms  and  graham 
flour  1.505  therms. 

One  hundred  pounds  of  wheat,  therefore,  when  manu- 
factured into  graham  flour  would  yield  151  therms  of 
energy,  or  82.5  per  cent,  of  its  total  content,  for  man's 
nutrition  as  compared  with  127  to  142  therms  recovered 
when  "straight"  flour  is  produced.    For  the  whole  wheat 

^  The  computations  are  based  upon  the  data  reported  by  Snyder 
in  U.  S.  Dept.  of  Agr.,  Office  Expt.  Stas.  Bulletins  101  and  126. 


WHEAT 


33 


flour,  assuming  the  bran  to  have  the  same  value  as  a 
stock  feed  as  that  produced  in  the  manufacture  of 
"straight"  flour,  the  figures  would  be  as  follows: 


Recovered 
in  animal 
products 

Recovered 

in  whole 

wheat  flour 

Total 
recovered 

Percentage 
recovery 

Offal  fed  to 

Cattle 

Sheep 

Pies 

Therms 

3.4 

3.8 

11.0 

9.3 

Therms 

135.0 
135.0 
135.0 
135.0 

Therms 
138.4 
138.8 
146.0 
144.3 

76 
76 
80 

Dairy  cows . . . 

79 

These  figures  make  it  appear  that  there  is  a  slight 
advantage  in  milling  to  86  or  87  per  cent,  and  a  greater 
advantage  still  in  leaving  all  the  bran  in  the  flour  as 
in  the  manufacture  of  graham  flour. 


VII 
CORN 

Unlike  wheat,  corn,  although  used  to  a  considerable 
extent  as  food  for  man,  is  popularly  regarded  in  the 
United  States  and  still  more  in  Europe  as  a  stock  feed, 
and  in  fact  only  a  small  percentage  of  the  corn  crop  of 
the  United  States  is  utilized  for  human  consumption. 

Besides  its  use  as  feed,  however,  corn  serves  as  the 
raw  material  in  other  manufacturing  processes  than 
milling,  such  as  the  manufacture  of  hominy  or  of  starch 
and  glucose  and  of  malt  and  distilled  liquors.  These 
various  processes  yield  by-products  useful  as  feeding 
stuffs  so  that  there  are  a  variety  of  possibilities  open 
regarding  the  utilization  of  corn  for  human  nutrition. 

Feeding  Directly. — Taking  first  its  utilization  di- 
rectly as  a  stock  feed,  one  hundred  pounds  of  average 
corn  contain  about  180.3  therms  of  gross  energy.  Of 
this  total  there  may  be  retained  in  the  body  or  the 
milk  of  an  animal  whose  maintenance  is  otherwise 
provided  for  85.5  therms  by  beef  cattle  and  sheep, 
108.4  therms  by  dairy  cows  and  118.8  therms  by  swine. 
Substantially  the  same  proportions  of  these  amounts 
as  in  the  case  of  wheat  would  be  lost  in  the  offal  and 
the  inedible  portions  of  the  carcass  and  expended  in 
the  digestion  of  the  edible  part  of  the  products.    Com- 

34 


CORN 


35 


puted  just  as  in  the  case  of  wheat,  the  final  recovery 
would  be  as  follows: 


Corn  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows 


Recovered  in 
animal  products 


Therms 

37.2 

42.1 

107.4 

102.0 


Percentage 
recovery 


21 
23 
60 

57 


Milling. — When  corn  is  milled  for  the  production  of 
table  meal  there  is  obtained  about  85  per  cent,  of  bolted 
meal  and  15  per  cent,  of  corn  bran.  A  pound  of  the 
meal  supplies  1.655  therms  of  energy  available  to  man, 
so  that  the  85  pounds  obtained  from  100  pounds  of 
corn  would  contain  140.7  therms  or,  as  in  the  case  of 
wheat,  considerably  more  than  can  be  recovered  in 
animal  products  when  the  corn  is  fed  to  live  stock. 

The  15  pounds  of  corn  bran  would  contain  about  28 
therms  of  total  energy.  When  used  as  feed  it  may  be 
estimated  that  there  would  be  utilized  by  cattle  and 
sheep  10.7  therms,  by  dairy  cows  13.5  therms,  and  by 
swine  15.0  therms.  The  relative  losses  in  the  inedible 
and  indigestible  material  of  the  meat  or  milk  would 
be  the  same  as  in  previous  cases.  Deducting  these 
and  adding  the  available  energy  of  the  85  pounds  of 
meal,  the  total  recovery  of  energy  for  human  nutrition 
in  this  case  would  be  as  follows: 


36      CONSERVATION  OF  FOOD  ENERGY 


Bran  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows 


Recovered 

Recovered 

Total 

products 

in  meal 

recovered 

Therms 

Therms 

Therms 

4.6 

140.7 

145.3 

5.2 

140.7 

145.9 

13.6 

140.7 

154.3 

12.7 

140.7 

153.4 

Percentage 
recovery 


81 
81 
86 
85 


Corn  is  also  milled  for  the  production  of  hominy, 
about  68  pounds  being  obtained  from  one  hundred 
pounds  of  corn.  The  by-products  (hulls,  germs  and 
scourings)  constitute  hominy  feed. 

A  pound  of  hominy  contains  1.65  therms  of  energy 
available  for  human  nutrition,  or  practically  the  same 
amount  as  corn  meal,  so  that  the  68  pounds  obtained 
from  one  hundred  pounds  of  corn  would  furnish  112.2 
therms. 

The  32  pounds  of  hominy  feed  would  contain  about 
59.2  therms  of  total  energy,  of  which  it  may  be  esti- 
mated that  there  could  be  utilized  under  average  con- 
ditions by  cattle  and  sheep  28.4  therms,  by  pigs  39.5 
therms  and  by  dairy  cows  36.0  therms.  Making  the 
same  percentage  deductions  as  before  for  the  inedible 
and  indigestible  portions,  the  net  amount  contributed 
to  human  nutrition  would  be  by  cattle  12.2  therms, 
by  sheep  14.0  therms,  by  pigs  35.7  therms  and  by  dairy 
cows  33.9  therms,  and  the  total  recovery  in  this  method 
of  utilizing  corn  would  be  as  follows: 


CORN 


37 


By-products  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows .... 


in  animal 
products 

Recovered 
in  hominy 

Total 
recovered 

Therms 

Therms 

Therms 

12.2 

112.2 

124.4 

14.0 

112.2 

126.2 

35.7 

112.2 

147.9 

33.9 

112.2 

146.1 

Percentage 
recovery 


69 
70 

82 
81 


Starch  and  Glucose. — In  the  manufacture  of  glucose 
from  com  the  starch  of  the  latter  is  separated  as  com- 
pletely as  practicable  by  mechanical  means  (grinding, 
sifting  and  washing)  and  subsequently  converted  into 
glucose.  The  residues  are  the  gluten  and  hulls  of  the 
corn  and  the  materials  dissolved  in  the  steep  water, 
together  constituting  gluten  feed,  and  the  germs  from 
which  the  corn  oil  is  pressed  leaving  as  a  residue  germ 
oil  cake.  From  one  hundred  pounds  of  corn  there  are 
obtained  24.5  pounds  of  gluten  feed,  3.5  pounds  of  germ 
oil  cake,  3  pounds  of  corn  oil  and  65  pounds  of  starch, 
equivalent  to  72.2  pounds  of  glucose.  Of  these  the  starch 
or  the  glucose  and  the  corn  oil  are  at  least  potentially 
available  for  human  food  while  the  gluten  feed  and  the 
germ  oil  cake  are  useful  only  for  animals.  Starch  sup- 
plies 1.86  therms  of  available  energy  per  pound,  equiva- 
lent to  1.67  therms  per  pound  of  glucose,  and  the  corn 
oil  may  be  reckoned  at  4.22  therms  per  pound.  The 
edible  products  from  100  pounds  of  corn  thus  treated 
would  therefore  supply  a  total  of  133.6  therms,  assum- 


38      CONSERVATION  OF  FOOD  ENERGY 

ing  the  oil  to  be  used  as  food,  or  120.9  therms  omitting 
the  oil. 

From  the  by-products  when  fed  to  stock  there  may 
be  recovered  in  the  body  or  the  milk  in  the  case  of 
gluten  feed  19.8  therms  by  cattle  or  sheep,  25.1  therms 
by  dairy  cows  and  27.5  therms  by  hogs.  For  the  germ 
oil  cake  the  corresponding  figures  would  be  2.9  therms 
by  cattle  and  sheep,  3.7  therms  by  dairy  cows  and  3.7 
therms  by  pigs.  Making  the  same  percentage  deduc- 
tions as  before  for  the  inedible  and  indigestible  portions 
of  the  animal  products,  we  get  as  a  final  result  per  100 
pounds  the  following: 


Recovered 
in  animal 
products 

Recovered 

in  glucose 

and  oil 

Total 
recovered 

Percentage 
recovery 

By-products  fed  to 
Cattle 

Therms 

9.9 

11.2 

28.2 

27.1 

Therms 
133.6 
133.6 
133.6 
133.6 

Therms 
143.5 
144.8 
161.8 
160.7 

80 

Sheep 

80 

Pigs 

Dairy  cows.  .  .  . 

90 
89 

Distilling. — Still  another  method  of  utilizing  corn  is 
as  the  raw  material  for  the  production  of  malt  and  dis- 
tilled liquors  or  of  alcohol. 

Of  the  seventy  and  one-half  million  bushels  of  grain 
reported  to  have  been  used  in  brewing  in  the  United 
States  in  1916,  corn  made  up  a  little  over  twenty-two 
per  cent.,  the  remainder  being  chiefly  barley  with  a 
little  rice.    The  recovery  of  food  value  in  brewing  may 


CORN  39 

therefore  be  more  advantageously  discussed  in  connec- 
tion with  barley. 

On  the  other  hand,  corn  is  an  important  source  of 
distilled  liquors  and  of  commercial  alcohol.  Based  on 
the  experience  of  distillers,  there  may  be  computed  from 
the  composition  of  corn  a  commercial  yield  of  17.9 
pounds  of  pure  alcohol  per  bushel,  or  32  pounds  per 
hundred.  Distillers  generally  use  mixed  grains  (corn, 
rye  and  malted  barley)  and  obtain  an  average  yield 
of  17.2  pounds  per  bushel  (56  pounds)  of  mixed  grain, 
equivalent  to  30.7  pounds  per  hundred  pounds  of  grain, 
a  result  confirming  the  figure  given  above  for  corn. 
The  by-product  of  distillation  is  distillers'  grains,  the 
yield  of  which,  in  the  dried  state,  may  probably  be 
estimated  to  be  about  the  same  as  that  of  brewers' 
grains  in  the  production  of  beer,  viz.,  28  pounds  per 
hundred  of  grain. 

The  28  pounds  of  dried  distillers'  grains  would  con- 
tain in  the  neighborhood  of  56  therms  of  total  energy, 
of  which  there  could  be  recovered  in  the  bodies  or 
milk  of  animals  to  which  it  was  fed,  on  the  same  assump- 
tions as  in  previous  cases,  23.8  therms  by  cattle  and 
sheep,  33.2  therms  by  pigs  and  30.2  therms  by  dairy 
cows.  Deducting  the  loss  in  the  inedible  and  indi- 
gestible materials,  there  would  be  recovered  as  human 
food,  10.4  therms  in  the  case  of  cattle,  11.7  therms  in 
the  case  of  sheep,  30.0  therms  in  the  case  of  pigs  and 
28.4  therms  in  the  case  of  dairy  cows. 

Food  Value  of  Alcohol. — The  final  conclusions  as  to 


40      CONSERVATION  OF  FOOD  ENERGY 

the  proportion  of  the  total  energy  of  the  corn  which  is 
recovered  for  human  nutrition  will  depend  upon  whether 
the  alcohol  is  regarded  as  a  food.  This  question,  in  the 
judgment  of  the  writer,  should  be  answered  in  the  nega- 
tive so  far  as  food  conservation  is  concerned. 

It  is  true  that  it  has  been  established  beyond  con- 
troversy that  dilute  alcohol  in  moderate  amounts  may 
not  only  be  burned  in  the  human  organism  but  may 
replace  an  equivalent  amount  of  such  materials  as 
carbohydrates  and  fats  which  are  universally  recog- 
nized as  foods.  On  this  basis  one  pound  of  pure  alcohol 
would  yield  3.14  therms  of  available  energy.  This, 
however,  by  no  means  warrants  placing  this  energy  on 
the  credit  side  of  the  account. 

First,  a  considerable  proportion  of  the  alcohol  pro- 
duced is  used  for  commercial  and  manufacturing  pur- 
poses and  does  not  enter  in  any  way  into  the  food 
supply. 

Second,  distilled  liquors  are  not  consumed  for  the 
sake  of  their  food  value  but  as  beverages  for  the  sake 
of  their  flavor  or  as  a  result  of  habit.  To  attempt  to 
supply  any  considerable  part  of  the  daily  food  require- 
ment in  this  way  would  almost  certainly  produce  more 
or  less  of  the  deleterious  effects  noted  in  the  next 
paragraph. 

Third,  the  physiological  effects,  other  than  nutritive, 
must  be  reckoned  with.  Quite  aside  from  the  familiar 
results  of  excessive  drinking,  and  the  dangers  of  alcohol 
as  a  habit-forming  drug,  it   appears  well  established 


CORN 


41 


that  its  effect  as  a  narcotic  on  the  nervous  system  and 
on  both  physical  and  mental  efficiency  goes  far  to  offset 
its  nutritive  value.  Alcohol  can  doubtless  be  utilized 
to  a  limited  extent  as  a  source  of  energy  for  the  human 
machine  but  its  use  deposits  grit  in  the  bearings  and 
slows  down  the  machine  so  that  it  is  very  questionable 
whether  it  adds  to  the  efeciive  food  supply. 

In  the  following  comparison,  however,  to  be  per- 
fectly impartial,  the  percentage  recovery  of  the  energy 
of  the  corn  has  been  computed  both  excluding  and  in- 
cluding the  possible  food  value  of  the  alcohol. 


Recovered 
in  animal 
products 

Recovered 
in  alcohol 

Percentage  recovery 

Excluding 
alcohol 

Including 
alcohol 

Distillers'  grains 
fed  to 

Cattle 

Sheep 

Pigs 

Therms 
10.4 

11.7 
30.0 
28.4 

Therms 
100.5 
100.5 
100.5 
100.5 

6 

6 

17 

16 

62 
62 

72 

Dairy  cows.  .  .  . 

72 

VIII 
BARLEY 


Barley  is  used  chiefly  as  a  feed  grain  and  in  the 
manufacture  of  beer,  comparatively  little  barley  flour 
having  been  produced  until  recently. 

Feeding  Directly. — Average  barley  contains  about 
184  therms  of  gross  energy  per  one  hundred  pounds. 
When  fed  directly  to  live  stock  it  may  be  estimated, 
in  precisely  the  same  way  as  in  the  case  of  wheat  or 
corn,  that  the  following  amounts  would  be  recovered 
for  man's  use  in  the  meat  or  milk  produced. 


Barley  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows 


Recovered  in 
animal  products 


Tlierms 
39.1 
44.3 
95.9 

107.3 


Percentage 
recovery 


21 
24 

52 
58 


Milling. — Barley  may  be  milled  to  produce  about 
80  per  cent,  of  flour.  Kellogg  and  Taylor,^  however, 
state  that  for  admixture  with  wheat  flour  a  60  per 
cent,  milling  gives  the  best  results.     Assuming  that 

1  The  Food  Problem,  p.  207.  The  Macmillan  Co.,  New  York, 
1917. 

42 


BARLEY 


43 


the  40  per  cent,  of  barley  feed  remaining  is  fed  and 
making  the  same  comparisons  as  with  wheat  and  corn, 
the  following  results  are  obtained,  showing,  as  before, 
a  much  greater  recovery  than  when  the  entire  grain 
is  used  as  feed. 


Barley  feed  used  for 

Cattle 

Sheep 

Pigs 

Dairy  cows 


Recovered 
in  animal 
products 


Therms 

12.7 
14.4 
37.4 
34.9 


Recovered 

Total 

in  flour 

recovered 

Therms 

Therms 

98.4 

111.1 

98.4 

112.8 

98.4 

135.8 

98.4 

133.3 

Percentage 
recovered 


60 
61 
74 

72 


Brewing. — In  1916  about  fifty-two  and  one-half 
million  bushels  of  barley,  or  about  twenty-nine  per 
cent,  of  the  total  crop,  were  used  in  the  United  States 
for  the  production  of  beer.  According  to  competent 
authorities,  one  hundred  pounds  of  barley  yield  in 
good  average  practice: 

Beer 421  lbs. 

Dried  brewers'  grains 28   " 

Malt  sprouts 4  " 

Dried  yeast 2   " 

The  beer  will  contain  about  0.5  per  cent,  of  protein, 
5.0  per  cent,  of  carbohydrates  (chiefly  dextrin-like 
substances)  and  3.5  per  cent,  of  alcohol.  Including 
the  alcohol,  the  421  pounds  of  beer  would  contain  88.3 
therms  of  energy  available  to  man,  while  excluding 
the  alcohol  reduces  the  amount  to  42.0  therms. 


44      CONSERVATION  OF  FOOD  ENERGY 

The  brewers'  grains,  malt  sprouts,  and  spent  yeast 
are  available  as  stock  feeds  and  the  recovery  of  food 
energy  from  each  may  be  computed  as  in  previous 
cases,  with  the  following  results: 


Energy  recovered  in  animal  products 

By  cattle 

By  sheep 

By  pigs 

By  dairy 
cows 

From  28  pounds  dried 
brewers'  grains .... 

From  4  pounds  malt 
sprouts 

Therms 
6.5 

1.3 

0.6 

8.4 

Therms 
7.4 

1.4 

0.7 

9.5 

Therms 
15.9 

3.1 

1.7 

20.7 

Therms 
17.8 

3.3 

From  2  pounds  dried 
yeast 

1.8 

22.9 

The  total  recovery  of  energy  in  the  beer  and  indi- 
rectly by  the  feeding  of  the  by-products  is  therefore 


Recov- 
ered in 
animal 
products 

Recovered  in  beer 

Percentage  recovery 

Including 
alcohol 

Excluding 
alcohol 

Including 
alcohol 

Excluding 
alcohol 

By-products  fed  to 

Cattle 

Sheep 

Therms 

8.4 

9.5 

20.7 

22.9 

Therms 
88.3 
88.3 
88.3 
88.3 

Therms 
42.0 
42.0 
42.0 
42.0 

53 
53 
59 
60 

27 
28 

Pigs 

34 

Dairy  cows 

35 

Even  if  the  alcohol  be  included,  the  recovery  of 
energy  is  notably  less  in  brewing  than  in  milling  al- 


BARLEY  45 

though  somewhat  greater  than  that  secured  when  the 
barley  is  used  directly  as  feed.  If  the  alcohol  be  not 
included,  the  recovery  in  brewing  is  much  less  than 
that  obtained  by  feeding  the  barley  to  pigs  or  cows 
and  little  if  at  all  greater  than  that  secured  by  feeding 
it  to  cattle  or  sheep. 


IX 


RYE 

Rye,  like  wheat,  may  be  fed  directly  to  live  stock 
or  may  be  milled  for  the  production  of  rye  flour,  while 
in  the  past  considerable  amounts  have  been  consumed 
in  the  manufacture  of  distilled  liquors. 

Feeding  Directly. — One  hundred  pounds  of  rye  con- 
tain about  184  therms  of  gross  energy.  When  fed  to 
live  stock  the  recovery,  computed  as  before,  is: 


Rye  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows 


Recovered  in 
animal  products 


Therms 

40.8 

46.1 

111.8 

111.8 


Percentage 
recovery 


22 
25 
61 
61 


Milling. — With  average  milling,  rye  yields  about  64 
per  cent,  of  flour  and  36  per  cent,  of  bran  and  shorts. 
One  pound  of  rye  flour  contains  1.63  therms  of  energy 
available  to  man  or  104.3  therms  in  the  64  pounds 
secured  from  one  hundred  pounds  of  rye.  The  energy 
recovered  by  feeding  the  36  pounds  of  milling  offal  to 
stock  and  the  total  recovery  in  flour  and  offal  are  there- 
fore as  follows: 

46 


RYE 


47 


Recovered 
in  animal 
products 

Recovered 
in  flour 

Total 
recovered 

Percentage 
recovery 

Bran  fed  to 

Cattle 

Sheep 

Pigs 

Daity  cows . 

Therms 
12.4 
14.1 
34.5 
34.1 

Therms 
104.3 
104.3 
104.3 
104.3 

Therms 
116.7 
134.4 

138.8 
138.4 

63 
64 

75 
75 

Distilling. — When  used  for  the  production  of  dis- 
tilled Uquor,  rye  is  stated  to  yield  some  five  per  cent, 
less  alcohol  than  com,  or  about  30.4  pounds  per  hun- 
dred pounds  of  rye.  Computed,  as  in  the  case  of  corn, 
both  with  and  without  the  alcohol,  the  recovery  of 
energy  in  the  edible  products  is: 


Distillers'  grains  fed  to 

Cattle 

Sheep 

Pigs 

Dairy  cows 


Recovered 
in  animal 
products 

Recovered 
in  alcohol 

Therms 

Therms 

6.8 

95.5 

7.7 

95.5 

19.8 

95.5 

18.7 

95.5 

Percentage  recovery 


Excluding 
alcohol 


4 

4 

11 

10 


Including 
alcohol 


56 
56 
63 
62 


X 


OATS.    RICE.    BUCKWHEAT 

Feeding  or  Milling. — Aside  from  the  relatively  small 
amoimt  of  rice  used  in  brewing,  these  grains  are  either 
used  directly  as  stock  feeds  or  milled  for  the  produc- 
tion of  table  meal  or  breakfast  foods.  The  estimation 
of  the  energy  recovery  by  the  two  methods  is  made 
precisely  as  in  previous  cases  and  as  before  shows  a 
much  higher  utilization  when  as  large  a  proportion  of 
the  grain  as  possible  is  consumed  directly  by  man. 
It  hardly  seems  necessary  to  give  the  details  of  the 
calculations.    The  final  results  are  as  follows: 


Percentage  recovery  of  energy 

Cattle 
Per  cent. 

Sheep 
Per  cent. 

Hogs 
Per  cent. 

Dairy  cows 
Per  cent. 

Oats 

Fed  direct 

Milled 

15 

58 

18 

57 

14 
56 

17 

58 

20 

58 

16 

57 

38 
64 

53 
62 

34 
40 

42 
64 

Rice 

Fed  direct 

Milled 

48 
62 

Buckwheat 

Fed  direct 

Milled  

38 
60 

48 


XI 


COTTONSEED 


Cottonseed  is  not  directly  available  as  food  for  man 
but  yields  an  edible  oil  which  is  coming  into  use  to 
an  increasing  extent,  while  from  the  press  residue 
(cottonseed  meal)  there  is  manufactured  a  cottonseed 
flour  which  promises  to  be  of  value  as  human  food. 

Feeding  Directly. — Cottonseed  contains  about  242 
therms  of  total  energy  per  one  hundred  pounds.  When 
it  is  fed  to  live  stock  the  recovery  of  energy  in  edible 
products,  computed  as  in  previous  instances,  may  be 
estimated  as  follows.  No  figures  have  been  computed 
for  swine  since  cottonseed  is  not  regarded  as  a  safe 
feed  for  this  species. 


Recovered  in 
animal  products 


Percentage 
recovery 


Cottonseed  fed  to 

Cattle 

Sheep 

Dairy  cows. . . . 


Therms 

31.1 
38.5 
93.5 


13 
16 
39 


Oil  Extraction. — In  the  cottonseed  oil  mills  one  hundred 
pounds  of  seed  yield  about  15.7  pounds  of  oil  and  49.7 
pounds  of  cake  or  meal,  the  remainder  being  hnters 
and  hulls  whose  feeding  value  is  for  the  present  pur- 
pose negligible.  From  the  49.7  pounds  of  cottonseed 
meal  there  may  be  recovered  in  edible  and  digestible 
form  in  the  carcass  or  milk  of  the  animal  to  which  it 

49 


50      CONSERVATION  OF  FOOD  ENERGY 

is  fed  the  amounts  shown  below,  while  the  oil,  if  used 
directly  as  human  food,  may  be  reckoned  at  4.22  therms 
per  pound,  or  a  total  of  66.3  therms,  so  that  the  total 
utilization  would  be  as  follows: 


Recovered 
in  animal 
products 

Recovered 
in  oil 

Total 
recovered 

Percentage 
recovery 

Cottonseed  meal  fed  to 
Cattle 

Therms 

19.4 
22.0 

53.3 

Therms 
66.3 
66.3 
66.4 

Therms 
85.7 
88.3 

119.6 

35 

Sheep 

36 

Dairy  cows 

49 

Cottonseed  Flour. — Cottonseed  flour  is  made  from 
cottonseed  meal  by  a  special  treatment  which  removes 
the  hulls  as  thoroughly  as  possible.  The  writer  has 
been  unable  to  secure  any  information  regarding  the 
yield  of  cottonseed  flour,  but  the  uata  regarding  its 
composition  seem  to  indicate  that  at  least  60  per  cent, 
of  prime  cottonseed  meal  may  be  recovered  in  the 
flour,  equivalent  to  29.8  pounds  from  one  hundred 
pounds  of  cottonseed.  On  the  basis  of  digestion  experi- 
ments it  may  be  estimated  that  a  pound  of  the  flour 
contains  1.53  therms  of  energy  available  for  human 
nutrition.  The  29.8  pounds  estimated  to  be  obtained 
from  100  pounds  of  cottonseed  would  accordingly  be 
equivalent  to  45.6  therms,  which  added  to  the  66.3 
therms  recovered  in  the  oil  makes  a  total  recovered  of 
111.9  therms,  or  46  per  cent.,  in  addition  to  whatever 
could  be  recovered  by  feeding  the  residue  from  the 
preparation  of  the  flour  to  live  stock. 


XII 
PEANUTS 

While  the  peanut,  either  as  the  roasted  nut  or  in  the 
form  of  peanut  butter,  is  usually  regarded  as  a  con- 
diment rather  than  as  a  food,  it  is  capable  of  con- 
tributing materially  to  human  nutrition.  There  is 
also  now  being  offered  in  the  market  a  peanut  flour, 
prepared  from  the  press  cake  left  in  the  manufacture 
of  peanut  oil,  while  the  oil  itself  if  properly  made  is  a 
valuable  food. 

The  writer  has  been  unable  to  secure  any  data  re- 
garding the  yield  of  peanut  flour  from  a  unit  of  raw 
material.  The  following  comparisons  therefore  are 
between  the  nuts  used  exclusively  as  human  food, 
exclusively  as  stock  feed,  or  for  the  manufacture  of 
oil,  the  press  cake  being  fed  to  animals.  All  the  data 
relate  to  the  hulled  nuts. 

Feeding  Directly. — One  hundred  pounds  of  hulled 
peanuts  contain  about  276.3  therms  of  energy.  When 
they  are  fed  directly  to  stock,  the  following  figures 
may  be  computed  in  the  same  manner  as  in  previous 
cases: 

5  51 


52      CONSERVATION  OF  FOOD  ENERGY 


Recovered  in 
animal  products 

Percentage 
recovery 

Peanuts  fed  to 
Cattle 

Therms 

47.4 

54.9 

122.9 

130.1 

17 

Sheep 

20 

Swine 

44 

Dairy  cows 

47 

Oil  Extraction. — One  hundred  pounds  of  hulled  pea- 
nuts are  stated  to  yield  60  pounds  of  peanut  cake  and 
40  pounds  of  oil.  The  oil  may  be  estimated  to  con- 
tain 4.22  therms  per  pound  of  energy  available  for 
man,  or  a  total  of  168.8  therms.  The  value  recovered 
from  the  cake  when  fed  to  stock  may  be  Estimated  as 
before  and  the  total  recovery  computed  as  follows: 


Peanut  cake  fed  to 

Cattle 

Sheep 

Swine 

Dairy  cows 


Recovered 
in  animal 
products 

Recovered 
in  oil 

Total 
recovered 

Therms 
24.4 
27.6 
63.3 
67.0 

Therms 
168.8 
168.8 
168.8 
168.8 

Therms 
193.2 
196.4 
232.1 
235.8 

Percentage 
recovery 


70 
71 
84 

85 


Finally,  one  hundred  pounds  of  peanuts  used  directly 
as  human  food  would  supply  256.0  therms  of  energy  or 
93  per  cent,  of  their  gross  energy. 


XIII 

MILK 

In  all  the  foregoing  comparisons  it  has  been  assumed 
that  the  milk  produced  by  dairy  cows  is  consumed 
directly  as  human  food.  Milk  itself,  however,  serves 
as  the  raw  material  for  the  manufacture  of  butter  or 
cheese  and  of  small  amounts  of  other  food  products. 

Butter  Making. — In  the  manufacture  of  butter  it  is 
possible  also  to  use  the  resulting  skim  milk  and  butter- 
milk as  human  food,  in  which  case  the  total  food  value 
may  be  considered  to  be  practically  the  same  as  that 
of  the  fresh  milk.  As  a  matter  of  fact  most  of  them 
are  fed  to  animals. 

One  hundred  pounds  of  4  per  cent,  milk  contain 
v30.6  therms  of  total  energy  of  which  28.8  therms,  or 
94  per  cent.,  is  available  to  man.  It  will  yield  about 
four  pounds  of  butter  containing  per  pound  3.61  therms 
of  available  energy,  or  a  total  of  14.42  therms,  12  pounds 
of  buttermilk  and  84  pounds  of  skim  milk.  When  the 
by-products  are  fed  to  calves  or  pigs,  the  amounts  of 
energy  recovered  in  the  edible  and  digestible  forms 
would  be: 

53 


54      CONSERVATION  OF  FOOD  ENERGY 


In  84  lbs. 
skim  milk 

In  12  lbs. 
buttermilk 

Total 

Fed  to 
Calves 

Therms 

5.23 
11.19 

Therms 
0.70 
1.45 

Therms 
5.93 

Pigs 

12.64 

Adding  the  amount  available  in  the  butter,  the  total 
recovery  would  be: 

Recovered 
in  animal 
products 

Recovered 
in  butter 

Total 
recovered 

Percentage 
recovery 

By-products  fed  to 
Calves 

Therms 

5.93 

12  64 

Therms 
14.42 
14.42 

Therms 
20.35 
27.06 

67 

Pigs 

89 

In  other  words,  the  percentage  recovery  when  butter 
is  manufactured  and  the  by-products  fed  to  animals  is 
about  70  to  90  per  cent,  as  compared  with  94  per  cent, 
when  the  milk  is  consumed  as  such.  The  estimates  of 
the  recovery  of  the  energy  of  various  materials  made 
in  previous  pages  must  evidently  be  reduced  in  this 
proportion  when  butter  instead  of  milk  is  the  main 
object  of  the  feeding. 

Cheese  Making. — In  the  manufacture  of  cheese,  the 
whey  is  practically  available  only  as  stock  feed. 

One  hundred  pounds  of  milk  will  yield  about  10 
pounds  of  cheese  and  90  pounds  of  whey.  Ten  pounds 
of  cheese  have  an  energy  value  of  19.5   therms  as 


MILK 


55 


human  food,  while  90  pounds  of  whey  would  yield  4.1 
therms  in  animal  products  when  fed  to  calves  and  8.5 
therms  when  fed  to  pigs  and  the  total  recovery  can  be 
tabulated  as  follows: 


XIV 
SUMMARY 

In  the  foregoing  pages  the  attempt  has  been  made 
to  compare  the  efficiency  of  the  various  methods  by 
which  some  of  the  more  important  farm  products 
may  be  made  to  contribute  to  the  food  supply.  The 
comparisons  are  based  solely  upon  the  proportion  of 
the  total  energy  of  these  products  which  can  be  recov- 
ered for  man's  use  and  take  no  account  of  the  relative 
utilization  of  the  protein  and  mineral  ingredients  nor 
of  the  presence  or  absence  of  accessory  ingredients 
(vitamines).  While  all  these  are  essential  requirements 
for  nutrition,  quantitatively  the  principal  function  of 
food  is  to  supply  energy  and  a  knowledge  of  the  relative 
amounts  of  energy  which  can  be  recovered  in  various 
methods  of  utilization  is  a  factor  of  prime  importance 
in  food  conservation. 

The  results  obtained  are  approximate  averages  only. 
Such  calculations  must  necessarily  be  based  on  average 
figures  and  refer  to  average  conditions.  Moreover, 
some  of  the  factors  employed  in  the  computations  are 
by  no  means  so  exactly  established  as  is  desirable. 
Consequently,  while  the  mathematical  computations 
are  believed  to  be  correct,  the  reader  should  beware  of 
56 


SUMMARY  57 

laying  too  much  stress  on  small  differences.     On  the 
other  hand  certain  broad  teachings  are  evident. 

Loss  in  Feeding. — The  most  obvious  of  these  is  the 
great  loss  of  energy  involved  in  the  conversion  of 
vegetable  into  animal  products,  that  is,  in  the  feeding 
of  live  stock.  It  is  here  assumed  that  the  maintenance 
of  the  animal  is  provided  for  by  a  sufficient  supply  of 
forage  of  one  sort  or  another,  so  that  the  body  resembles 
a  factory  already  supplied  with  sufficient  power  to  run 
the  emp'ty  machinery.  Even  under  these  conditions, 
however,  with  none  of  the  energy  of  the  added  grain 
expended  in  supporting  the  overhead  cost,  it  appears 
that  from  thirty-nine  to  as  much  as  eighty-six  per  cent, 
of  the  energy  of  grains  consumed  by  animals  is  lost  in 
one  way  or  another  and  only  from  fourteen  to  sixty- 
one  per  cent,  is  recovered  for  man's  use.  Obviously, 
the  diversion  to  stock  feeding  of  any  material  edible  by 
man  is  from  this  standpoint  a  very  wasteful  proceeding. 

Comparison  of  Animals. — Another  fact  which  appears 
clearly  is  that  the  percentage  recovery  of  energy  in 
animal  products  differs  widely  with  the  nature  of  the 
animals  fed.  In  this  respect  cattle  and  sheep  form  one 
distinct  group  and  pigs  and  dairy  cows  another,  the 
differences  within  each  group  being  relatively  small. 
In  the  production  of  beef  and  mutton  the  loss  is  very 
large,  ranging  from  seventy-five  to  eighty-six  per  cent. 
This  is  due  in  part  to  the  extensive  fermentation  which 
occurs  in  the  stomach  of  cattle  and  sheep  and  in  part 
to  the  relatively  large  proportion  of  inedible  material 


58      CONSERVATION  OF  FOOD  ENERGY 

contained  in  their  bodies.  In  pork  and  milk  produc- 
tion the  losses  are  notably  smaller,  ranging  from  thirty- 
nine  to  sixty-six  per  cent.  The  body  of  the  pig  contains 
much  less  inedible  matter  than  that  of  the  steer  or  the 
sheep  and  his  feed  is  subject  to  fermentation  to  a  far 
less  degree  than  in  ruminants.  In  milk  production  the 
conversion  appears  to  be  decidedly  more  efficient  than 
in  meat  production  while  there  is  no  inedible  waste. 

Inedible  Products  Saved.— On  the  other  hand,  the 
animal  performs  a  most  important  function  in  the 
utilization  of  products  inedible  by  man.  The  various 
forage  crops  and  the  inedible  by-products  of  manu- 
facturing can,  through  the  medium  of  the  animal,  be 
made  tributary  to  man's  support.  It  is  true  that  there 
may  be  an  even  greater  loss  in  the  conversion  than 
obtains  with  the  grains  but  whatever  is  thus  recovered 
is  so  much  added  to  the  food  supply  and  the  importance 
of  utilizing  these  materials  to  the  greatest  practicable 
extent  can  hardly  be  overemphasized. 

Milling  vs.  Feeding. — It  is  clear,  then,  that  the  en- 
deavor should  be  to  utilize  as  large  a  proportion  of 
vegetable  products  as  is  possible  directly  as  human 
food,  leaving  only  the  by-products  to  be  fed  to  stock. 
In  the  case  of  the  cereals  this  is  accomplished  chiefly 
by  some  form  of  milling.  The  total  recovery  of  energy 
effected  in  this  way  is  relatively  high,  ranging  from 
fifty-six  to  eighty-one  per  cent,  when  the  offals  are  used 
for  beef  and  mutton  production  and  from  sixty  to  eighty- 
live  per  cent,  when  they  are  used  for  pork  and  milk 


SUMMARY 


59 


production,  as  appears  from  the  following  comparison 
of  the  percentage  recovery  in  this  way  with  that  se- 
cured by  feeding  the  same  materials  directly  to  ani- 
mals. 


Wheat 

Com 

Barley.  .  .  . 

Rye 

Oats 

Rice 

Buckwheat 


Average  percentage  recovery  of  energy 


With  cattle  and  sheep 


Fed 
directly 


23 

22 

23 
24 
16 
19 
15 


Milled  and 
offals  fed 


701 

812 

703 

61 

64 

58 

57 

56 


With  pigs  and  dairy 
cows 


Fed 
directly 


57 

58 

55 
61 
40 
50 
36 


Milled  and 
offals  fed 


771 
852 
82' 
73 
75 
64 
62 
60 


Vegetable  Oils. — In  the  case  of  the  oil-bearing  seeds 
a  high  percentage  recovery  may  also  be  computed  on 
the  assumption  that  the  resulting  vegetable  oils  are 
used  for  food  purposes,  an  assumption  which  appears 
to  be  far  from  corresponding  with  present  facts.  Sim- 
ilarly, a  high  recovery  is  estimated  in  the  manufacture 
of  starch  and  glucose  only  on  the  assumption  that 
these  products  are  all  utilized  as  food. 

Brewing  and  Distilling. — The  brewing  and  distilling 

*  Usual  73  per  cent,  milling.  2  Milled  for  table  meal. 

'  Milled  for  hominy. 


60       CONSERVATION  OF  FOOD  ENERGY 


industries,  on  the  contrary,  show  a  very  low  utiliza- 
tion of  the  energy  of  their  raw  materials  unless  the 
full  theoretical  food  value  is  assigned  to  the  alcohol 
produced.  Only  some  twenty-eight  to  thirty-five  per 
cent,  is  recovered  in  other  products  in  brewing  and 
only  from  four  to  sixteen  per  cent,  in  distilling.  Even 
if  the  alcohol  be  included  in  the  computation  the  re- 
covery is  still  notably  lower  than  that  obtained  by 
milling  the  same  materials,  as  appears  from  the  fol- 
lowing tabulation: 


Percentage  recovery  of  energy 

Offals  fed  to  cattle  or 
sheep 

Offals  fed  to  pigs  or 
dairy  cows 

Including 
alcohol 

Excluding 
alcohol 

Including 
alcohol 

Excluding 
alcohol 

In  brewing 

Barley 

In  distilling 

Corn 

53 

62 
56 

28 

6 
4 

60 

72 
62 

35 
16 

Rye 

11 

NDEX 


Alcohol,  food  value  of,  39 
Animals,  comparison  of,  57 

eflSciency  of,  as  converters, 
18 

food  value  of  increase  by,  22 

Barley  flour,  energy  value  of, 

17 

net  energy  value  of,  20 

recovery  of  energ>'  from,  by 

brewing,  43,  44,  60 

by    feeding    directly, 

42,59 
by  milling,  42,  43 
Beer,  energy  value  of,  17 
Brewing,  recovery  of  energy  in, 

43,  44,  59,  60 
Buckwheat  flour,  energy  value 
of,  17 
net  energy  value  of,  20 
recovery  of  energy  from,  by 
feeding    directly,    48, 
59 
by  milling,  48,  59 
Butter,  energy  value  of,  17 
making,  recovery  of  energy 
in,  53,  54 
Buttermilk,  net  energy  value 
of,  20 


Cattle,  food  value  of  increase 
by,  22 
recovery  of  energj^  by,  57,  58 
Cheese,  energy  value  of,  17 
making,  recovery  of  energy 
in,  54,  55 
Corn  crop,  energy  of,  12 
meal,  energy  value  of,  17 
oil,  energy  value  of,  17 
recovery  of  energy  from,  by 
distilling,  38,  40,  60 
by  feeding  directly,  34, 

35,59 
by  glucose  manufacture, 

37,38 
by  milling,  35,  36,  37,  59 
by  starch  manufacture, 
37,38 
Cottonseed  flour,  50 
energy  value  of,  17 
net  energy  value  of,  20 
oil,  energy  value  of,  17 
recovery  of  energy  from,  by 
cottonseed  flour,  50 
by  feeding  directly,  49 
by  oil  extraction,  49,  50 

Dairy  cows,  food  value  of  in- 
crease by,  24 


61 


62 


INDEX 


Dairy  cows,  recovery  of  energy 

by,  57,  58 
Distilling,  recovery  of  energy 

in,  38,  41,  47,  59,  60 


Efficiency  of  animal  as  con- 
verter, 18 
Energy    as    measure    of    food 
value,  12 
loss  of,  in  feeding,  57 
of  farm  crops,  availability  of, 

13 
recovery  of,  by  cattle,  57,  58 
by  dairy  cows,  57,  58 
by  pigs,  57,  58 
by  sheep,  57,  58 
from  barley,  42,  59,  60 
from  buckwheat,  48,  59 
from  corn,  34,  59,  60 
from  cottonseed,  49 
from  milk,  53 
from  oats,  48,  59 
from  peanuts,  51 
from  rice,  48,  59 
from  rye,  46,  59,  60 
from  wheat,  29,  59 
in  animal  products,  18 
in  brewing,  43,  44,  59,  60 
in  butter  making,  53,  54 
indistilling,  38,  41,47,  59, 

60 
in  feeding  directly,  29,  30, 
34,35,42,46,48,51,52, 
58,59 


Energy,  recovery  of,  in  glucose 
manufacture,  37,  38 
in  graham  flour,  32 
in  milling,  30,  31,  33,  35, 
36,  37,  42, 43,  46, 47,  58, 
59 
in  oil  extraction,  49,  52 
in  starch  manufacture,  37, 

38 
in  whole  wheat  flour,  32, 
33 
supplied  by  food,  11,  12,  16 
values,  net,  19,  20 
of  foods,  17 

Factors  of  food  conservation, 

13 
Farm    crops,    availability    of 
energy  of,  13 
efficiency  of  utilization  of, 

8 
inedible,  7,  58 
methods  of  utilization  of, 
8 
Fats,  importance  of,  14 
Feed  cost,  overhead,  25 
Feeding  directly,   recovery  of 
energy  in,  29,  30,  34,  35, 
42,  46,  48,  49,  51,  52,  58, 
59 
versus  milling,  58,  59 
Food  conservation,  factors  of, 
13 
energy  supplied  by,  11,  12, 
16 


INDEX 


63 


Food  energy,  values  of,  17 
material  for  growth  supplied 

by,  11 
mineral  substances  supplied 

by,  11 
protein  supplied  by,  11 
substances  supplied  by,  12 
value,  measure  of,  11 
of  alcohol,  39 
of  increase  by  cattle,  22 
by  dairy  cows,  24 
by  pigs,  23 
by  sheep,  22 
Forage  crops  for  production,  28 
maintenance  by,  26 
value  of,  20 

Glucose,  energy  value  of,  17 
manufacture,  recovery  of  en- 
ergy in,  37,  38 
Graham  flour,  32 

energy  value  of,  17 
recovery  of  energy  in,  32 
Grain    necessary    in    intensive 

feeding,  26 
Growth,  material  for,  supplied 
by  food,  11 

Hominy,  energy  value  of,  17 

Increase    by    animal,     food 
value  of,  32 
not  all  edible,  22 
Inedible  products  saved,  58 


Loss  of  energy  in  feeding,  57 

Maintenance  by  forage  crops, 
26 
requirement,  25 
Milk,  energy  value  of,  17 

recovery  of,   in   butter 
making,  53,  54 
in  cheese  making,  54, 
55 
Milling,  recovery  of  energy  in, 
30,  31,  33,  35,  36,  37,  42, 
43,  46,  47,  48,  58,  59 
versus  feeding,  58,  59 
Mineral  substances  supplied  by 
food,  11 

Net  energy  values,  19,  20 

Oatmeal,  energy  value  of,  17 
Oats,  recovery  of  energy  from, 
by    feeding    directly, 
48,59 
by  milling,  48,  59 
Oil  extraction,  recovery  of  en- 
ergy in,  49,  52 
Overhead  feed  cost,  25 

Peanut,  energy  value  of,  17 
net,  20 
oil,  energy  value  of,  17 
recovery  of  energy  from,  by 
feeding   directly,    51, 
52 
by  oil  extraction,  52 


64 


INDEX 


Pigs,  food  value  of  increase  by, 
23 
recovery  of  energy  by,  57,  58 
Protein  supplied  by  food,  11 

Recovery  of  energy  by  cattle, 

57,58 
by  dairy  cows,  57,  58 
by  pigs,  57,  58 
by  sheep,  57,  58 
from  barley,  42,  59,  60 
from  buckwheat,  48,  59 
from  corn,  34,  59,  60 
from  cottonseed,  49 
from  milk,  53 
from  oats,  48,  59 
from  peanuts,  51 
from  rice,  48,  59 
from  rye,  46,  59,  60 
from  wheat,  29,  59 
in  animal  products,  18 
in  brewing,  43,  44,  59,  60 
in  butter  making,  53,  54 
in  cheese  making,  54,  55 
in  distilling,  34,  41,  47,  59, 

60 
in  feeding  directly,  29,  30, 

34,  35,  42,  46,  48,  49, 

51,  52,  58,  59 
in    glucose    manufacture, 

37,38 
in  graham  flour,  32 
in  milling,  30,  31,  33,  35, 

36,  37,  42,  43,  46,  47,  48, 

58,59 


Recovery  of  energy  in  oil  ex- 
traction, 49,  52 
in  starch  manufacture,  37, 

38 
in  whole  wheat  flour,  32, 
33 
Rice,  polished,  energy  value  of, 
17 
recovery  of  energy  from,  by 
feeding  directly,  48, 59 
by  milling,  48,  59 
rough,  net  energy  value  of,  20 
Rye  flour,  energy  value  of,  17 
net,  20 
recovery  of  energy  from,  by 
distilling,  47,  60 
by  feeding  directly,  46, 

59 
by  milling,  46,  47,  59 

Sheep,  food  value  of  increase 
by,  23 

recovery  of  energy  by,  57,  58 
Skim  milk,  net  energy  value  of, 

20 
Species,  dififerent,  recovery  of 

energy  by,  57,  58 
Starch  manufacture,  recovery 

of  energy  in,  37,  38 

Therm,  16 

Utilization    of    farm    crops, 
efficiency  of,  8 


INDEX 


65 


Utilization     of     farm     crops, 
methods  of,  8 

VlTAMiNES  supplied  by  food,  12 

Wheat  flour,  energy  value  of, 
17 
net  energj'  value  of,  20 


Wheat,  recovery  of  energy  from, 
by  feeding  directly,  29, 
30,  59 
by  milling,  30,  59 
Whole  wheat  flour,  32 

recovery  of  energy  in,  32, 
33 


This  book  is  DUE  on  the  last  date  stamped  below 


OF;-  -:•  i1Q^a\}^ 


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Form  L-9-15to-H,'27 


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